A process of this type is described in EP-A-0.524.880, in the name of the applicant.
The use of a burner with pulsed supply according to this document permits reducing substantially the emissions of nitrogen oxide. However, for installations of high power, with high flow rates of fluids, the reduction of nitrogen oxides is less great and there have been experienced moreover substantial variations of the volume of smoke and an increase of CO emission, which could be attributed to fluctuating and poorly controlled air inputs into the furnace.